The paper compares duplex stainless steels to the traditional austenitic grades. It discusses austenitic-ferritic or duplex grades that are entering the industrial sector. The paper also describes applications within desalination where the duplex grades have been used and the reasons behind their choice. The duplex stainless steels have good resistance to corrosion, especially to stress corrosion cracking (SCC), they have about twice the strength of austenitic grades, they are more price-stable due to lower contents of mainly nickel and molybdenum, and they are excellent engineering materials